We will continue our efforts to identify the potent immunosuppressive substance in amniotic fluid and to determine whether this could possibly be a contaminant present in apparently homogeneous preparations of AFP. Synthesis of AFP by GVH spleens will be correlated with several immune parameters as well as the subsequent development of lymphoma. We will also continue to test for AFP-bearing lymphocytes and synthesis of AFP by lymph nodes and splenic tissues from patients with various lymphomas and to correlate this with both immunosuppression and the histological type of the tumor. Various human tumors in which AFP may possibly be produced, such as gastrointestinal tumors, will be grown in nude mice and both the serum and tumor tissues of these animals will be analyzed for AFP by radioimmunoassay and the tumors by in vitro synthesis techniques. We have also begun to apply the surface lactoperoxidase labeling technique to study surface markers on both malignant cells and cells undergoing allogeneic reactions.